Progressive decline of arterial oxygen saturation measured by pulse oximetry in the patient with inferior vena cava obstruction: delayed impact of inherited haemoglobinopathy.

Although inherited haemoglobinopathies may indicate low oxygen saturation measured by pulse oximetry (SpO2), the timing and mode of its decline after birth are unclear. Here, we present a patient with haemoglobin Köln disease who developed unexpected decline in SpO2 more than two years after heart surgery. Due to simultaneous identification of inferior vena cava stenosis, the differential diagnosis became complicated.